Question

why there is no force acting along string in simple pendulum

Answer 1

Answer:

The Simple Pendulum. A simple pendulum is defined to have a point mass, also known as the pendulum bob, which is suspended from a string of length L with negligible mass (Figure 15.5. ... Here, the only forces acting on the bob are the force of gravity (i.e., the weight of the bob) and tension from the string.